Various types of infrared position/image sensors have been developed for determining the position of or the image shape of an infrared radiation source. The image sensors are designed to convert an infrared image to a visual image. Infrared sensors generally are of either a cooled or uncooled variety. The cooled variety, usually cooled by liquid nitrogen or thermal-electric cooling, are used where high-speed, fast response times are required. However, such cooled types of sensors are usually expensive and technically cumbersome to use. The image sensing system usually requires either a plurality of discrete elements that are mechanically scanned or arrays that are electronically scanned. While infrared detectors that are uncooled are simpler and relatively inexpensive, they exhibit slow response times and are not generally applicable to image or position sensing. Bismuth film detectors have been developed which have been used as position sensors but have not yet proved to be very reliable in operation.